Villacidro Spa e Giovanni Giudici

Yesterday we got the opportunity to explore our second waste treatment plant of the trip, Villaservice Spa in Villacidro. In contrast to the last plant that we visited, this one featured both an anaerobic digester and an active solid waste landfill. The industrial zone it was in also had a sewage treatment plant, photovoltaic solar installations, and a wind farm. However, we were only able to visit the solid waste plant.

Prior to touring the actual plant, a plant engineer presented about the setup and statistics regarding its capacity. The landfill has 3 separate sections. One operated from 1993 until 2008, and has since been closed and capped. Decomposing organic matter within the landfill creates a mixture of CO2 and CH4 (methane), called biogas, that can be captured and burned for energy. The section is expected to produce biogas for the next 30 years. The second section is currently being filled, and is slated to close in 2018. Biogas extraction will begin on this one once it has been filled and capped. The last section remains undeveloped. It will be put into use once the other landfill is closed.

27 extraction wells drilled 70 feet into the closed landfill collect biogas

A bulldozer arranges newly dumped waste before it is compacted in the active landfill

We got to walk around the closed landfill, which looks like a big flat hill except for the biogas wells. From there we could see across to the active landfill, which looked much more like what one would expect. Every time the machines moved, hundreds of seagulls swooped into the air to avoid being crushed. If you're looking to do an Alfred Hitchcock reboot with seagulls, it would appear that a landfill is the place to be. 

The rest of the plant is designed to treat organic waste. This includes food waste, brush and yard waste, and waste paper. The organic waste is either composted to create a rich fertilizer or sent to an anaerobic reactor to create biogas. For the anaerobic digester, scrap metal is removed from the organic matter, then it is shredded, mixed with sand and water, and stored until it can be treated. In the reactor, bacteria that thrive in oxygen-deprived conditions convert the waste into methane and CO2. The methane is sent to a storage tank on the facility, where it is burned in special engines to create electricity. The whole process involves a lot of heavy machinery as well as conditions that aren't very friendly to humans, so unfortunately we weren't able to observe much but the outside of the components. 

The crane operator's chair overlooking mounds of piled waste

Piping brings biogas from the anaerobic reactor and the landfill to a methane storage bubble, seen in the background

Overall, the trip to this landfill was much less pleasant than the last one. A terrible odor pervaded the whole place, and even with a face mask on it was exceedingly strong at points. Runaway trash was everywhere, and all sorts of rubbish was on the ground. Flies buzzed around us, and seagulls could be seen everywhere picking at trash. The one bright spot was our super friendly and helpful tour guide, the plant engineer, who we somehow convinced to 'bless up'. 

Seagulls perch on a roof, staying out of range of a hawk kite floating nearby

The plant engineer confusedly blesses up 

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Today Giovanni de Giudici, a geologist at the University of Cagliari, spoke spoke to us regarding mine cleanup in the San Giorgio Region of Sardinia. Porto Flavia, where we visited two weeks ago, is part of this region that was heavily mined for zinc, lead, and other metals. The area is now a major tourist destination, known for its beautiful beaches and rocky coastline. While the mining may have stopped, its effects on the environment have not. The mine tailings (leftover material after extraction) dot the landscape, leaching harmful metals into the water and air. Remediation of these polluted areas is necessary to continue the tourism industry, as well as protect local populations from long-term health hazards.

Giudici explained some of the sampling methods he and other researchers used to quantify the amount of metals leaching into the San Giorgio River. He also explained the difficulties of analyzing different remediation plans for their effectiveness. The plan that is currently selected has impacts on all members of the community, and while it would contain the mine tailings in the long term, in the short term it could release even more metals from the soil. 

A quick Google Scholar search of Giudici shows he has been very productive with research in this subject. Two papers related to his lecture can be found here and here.